Mail (maille, chainmail) is a type of armour consisting of small metal rings linked together in a pattern to form a mesh.

Mail first appeared some time after 300 BC. Its invention is credited to the Celts. It may have been inspired by the much earlier scale armour. Mail spread to North Africa, the Middle East, Central Asia, India, Tibet, Korea and Japan.

Mail continues to be used in the 21st century as a component of stab-resistant body armour, cut-resistant gloves for butchers and woodworkers, shark-resistant wetsuits for defence against shark bites, and a number of other applications.

The origins of the word “mail” are not fully known. One theory is that it originally derives from the Latin word macula, meaning "spot" or “opacity” (as in macula of retina). Another theory relates the word to the old French “maillier”, meaning “to hammer” (a cognate of the modern English word “malleable”).

The first attestations of the word “mail” are in Old French and Anglo-Norman: “maille” “maile”, or “male” or other variants, which became “mailye” “maille” “maile”, “male”, or “meile” in Middle English.